If you want to burn more calories, lose more fat, and improve your fitness level while spending less time exercising, it may be time for you to try HIIT[1].

Just about any exercise[2] will work for high-intensity interval training, or HIIT, such as working out on an elliptical machine or treadmill. (Photo by Cyrus McCrimmon, The Denver Post)

HIIT or high-intensity interval training, could be exactly what you need if you struggle with time to get your exercise in, need to bust through a fat loss[3] plateau or want to take your training to the next level.

Before we go any further, I need to point out that I didn’t say HIIT would be easier, just that it would take less time. In fact, HIIT exercise is very physically demanding, and it isn’t for everyone.

If you have any cardiovascular problems or other health concerns that limit your ability to exercise at very intense levels, or if you are relatively new to aerobic exercise or not already in pretty good shape, HIIT is not for you — at least not for now. If you have any doubts or concerns about whether it might be safe for you, check with your medical professional before trying HIIT.

HIIT is a form of interval training that involves short bursts of maximum intensity exercise paired with or separated by moderate intensity exercise or rest periods. Because it involves pushing yourself beyond the upper end of your aerobic exercise zone, it offers a number of exciting benefits that traditional steady-state exercise does not.

Here are some of my favorite benefits:

#1 HIIT increases the amount of calories you burn during and after your exercise session because it increases the length of time it takes your body to recover. Long after you leave the gym, your metabolism stays revved up and you continue to burn calories[4] and fat! How cool is that?

#2 HIIT causes metabolic adaptations that enable you to use more fat as fuel under a variety of conditions. This will improve your athletic endurance and your fat-burning potential. Yippee!

#3 HIIT trains and conditions both your anaerobic and aerobic energy systems. This translates into having a stronger heart and being able to more easily endure rigorous activity. Perfect for the upcoming ski season!

#4 HIIT limits muscle loss that can occur with weight loss[5] achieved through traditional steady-state cardio[6] exercise. Keeping and building lean muscle mass is the key to being lean. Your muscle mass is one of the biggest consumers of energy in the body, and the more you have, the better your fat loss.

HIIT is based on the latest science that highlights how and why intensity matters. So let’s talk intensity. Exercise intensity is a subjective measure of how hard physical activity feels when you’re doing it. Apparently we all tend to overestimate how hard we actually work in our workouts….I was a little sad to learn this tidbit.

On a scale of 1-10:1 is sitting in a chair3 is walking5-6 is working out7-8 is working out hard9-10 is giving everything — I mean everything you have since 11 would be complete exhaustion.

The key to HIIT is that it requires maximum effort, not just an elevated heart rate. I tell my clients to imagine they are outrunning a tidal wave, racing to save a child from oncoming traffic, or running from an axe murderer. You get the picture. Go as hard and fast as you can!

Because HIIT is physically demanding, it is important to gradually build up your training program so that you don’t overdo it. As always, warm up and cool down before any exercise session. If you feel faint, dizzy, sick or have chest pains stop and cool down immediately. (Don’t just stop because blood can pool in your extremities and can feel dizzy or faint)

Almost any activity can be used for HIIT training:
Running, sprinting, biking, Stairmaster, treadmill, the elliptical machine, kettlebell swings, box jumps, squat jumps, thrusters, push ups, jump rope, power cleans, sled pulling — or really anything you can safely do at a high intensity for about 30 seconds.

The idea is to go as hard as you can for a relatively short period of time, rest and then repeat until you reach your goal.

Remember, balance is always the key, so don’t swap all your exercise for HIIT. Two HIIT sessions per week instead of or in addition to what you are already doing will do the trick. Believe it or not you can exercise too much! Too much exercise stresses the body out and can even cause your body to go into survival mode and store fat-definitely NOT the outcome we are looking for! Keep in mind that motivation, accountability and moderation are the keys to long term success.

So, challenge yourself but don’t drive yourself into the ground. Listen to your body when it tells you to rest or back off.

Give HIIT a try and get ready to see major changes in your body and fitness level. You’ll burn more calories and fat than ever before in the least amount of time.